递归创建目录的一个函数

下面是从openid的php代码中看到的一个递归创建目录的函数，感觉是比较简洁的，值得参考

<?php
    function ensureDir($dir_name)                                                 
    {                                                                             
        if (is_dir($dir_name) || @mkdir($dir_name)) {                             
            return true;                                                          
        } else {                                                                  
            $parent_dir = dirname($dir_name);                                     
                                                                                  
            // Terminal case; there is no parent directory to create.             
            if ($parent_dir == $dir_name) {                                       
                return true;                                                      
            }                                                                     
                                                                                  
            return (ensureDir($parent_dir) && @mkdir($dir_name));    
        }                                                                         
    }  
?>